The present invention relates to a semiconductor device and a method of manufacturing the same, and particularly, to a semiconductor device having a heterojunction and a method of manufacturing the same.
Japanese Laid-Open Patent Publication No. 2003-318413 discloses a semiconductor device having a semiconductor base made of an n+-type silicon carbide substrate region and an n−-type epitaxial region formed on the substrate region. On one principal face of the semiconductor base, an n-type polysilicon region is formed. The epitaxial region and n-type polysilicon region form a heterojunction. In contact with an end of the heterojunction, a p-type electric field relaxation region is formed. On a bottom face of the n+-type silicon carbide substrate region, a bottom electrode is formed. On the surface of the polysilicon region, a surface electrode is formed.
On the other hand, a Schottky junction is a junction that uses conventional silicon carbide to provide a diode having a high withstand voltage as described in “Power Device/Power IC Handbook,” Japanese Electrotechnical Committee, High-Performance, High-Function Power Device/Power IC Research Expert Committee, Corona Publishing Co., Ltd., p.p. 12–21 (nonpatent literature). The junction described in this nonpatent literature is based on silicon and is widely applied to silicon carbide.